ipv6: Separate ipv6 offload support

Separate IPv6 offload functionality into its own file
in preparation for the move out of the module

Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 273 insertions, 0 deletions

diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
new file mode 100644
index 000000000000..01cf9835a581
--- /dev/null
+++ b/net/ipv6/ip6_offload.c
@@ -0,0 +1,273 @@
+/*
+ *      IPV6 GSO/GRO offload support
+ *      Linux INET6 implementation
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/socket.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+
+#include <net/protocol.h>
+#include <net/ipv6.h>
+
+#include "ip6_offload.h"
+
+static int ipv6_gso_pull_exthdrs(struct sk_buff *skb, int proto)
+{
+        const struct net_offload *ops = NULL;
+
+        for (;;) {
+                struct ipv6_opt_hdr *opth;
+                int len;
+
+                if (proto != NEXTHDR_HOP) {
+                        ops = rcu_dereference(inet6_offloads[proto]);
+
+                        if (unlikely(!ops))
+                                break;
+
+                        if (!(ops->flags & INET6_PROTO_GSO_EXTHDR))
+                                break;
+                }
+
+                if (unlikely(!pskb_may_pull(skb, 8)))
+                        break;
+
+                opth = (void *)skb->data;
+                len = ipv6_optlen(opth);
+
+                if (unlikely(!pskb_may_pull(skb, len)))
+                        break;
+
+                proto = opth->nexthdr;
+                __skb_pull(skb, len);
+        }
+
+        return proto;
+}
+
+static int ipv6_gso_send_check(struct sk_buff *skb)
+{
+        const struct ipv6hdr *ipv6h;
+        const struct net_offload *ops;
+        int err = -EINVAL;
+
+        if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
+                goto out;
+
+        ipv6h = ipv6_hdr(skb);
+        __skb_pull(skb, sizeof(*ipv6h));
+        err = -EPROTONOSUPPORT;
+
+        rcu_read_lock();
+        ops = rcu_dereference(inet6_offloads[
+                ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr)]);
+
+        if (likely(ops && ops->gso_send_check)) {
+                skb_reset_transport_header(skb);
+                err = ops->gso_send_check(skb);
+        }
+        rcu_read_unlock();
+
+out:
+        return err;
+}
+
+static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
+        netdev_features_t features)
+{
+        struct sk_buff *segs = ERR_PTR(-EINVAL);
+        struct ipv6hdr *ipv6h;
+        const struct net_offload *ops;
+        int proto;
+        struct frag_hdr *fptr;
+        unsigned int unfrag_ip6hlen;
+        u8 *prevhdr;
+        int offset = 0;
+
+        if (!(features & NETIF_F_V6_CSUM))
+                features &= ~NETIF_F_SG;
+
+        if (unlikely(skb_shinfo(skb)->gso_type &
+                     ~(SKB_GSO_UDP |
+                       SKB_GSO_DODGY |
+                       SKB_GSO_TCP_ECN |
+                       SKB_GSO_TCPV6 |
+                       0)))
+                goto out;
+
+        if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
+                goto out;
+
+        ipv6h = ipv6_hdr(skb);
+        __skb_pull(skb, sizeof(*ipv6h));
+        segs = ERR_PTR(-EPROTONOSUPPORT);
+
+        proto = ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr);
+        rcu_read_lock();
+        ops = rcu_dereference(inet6_offloads[proto]);
+        if (likely(ops && ops->gso_segment)) {
+                skb_reset_transport_header(skb);
+                segs = ops->gso_segment(skb, features);
+        }
+        rcu_read_unlock();
+
+        if (IS_ERR(segs))
+                goto out;
+
+        for (skb = segs; skb; skb = skb->next) {
+                ipv6h = ipv6_hdr(skb);
+                ipv6h->payload_len = htons(skb->len - skb->mac_len -
+                                           sizeof(*ipv6h));
+                if (proto == IPPROTO_UDP) {
+                        unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
+                        fptr = (struct frag_hdr *)(skb_network_header(skb) +
+                                unfrag_ip6hlen);
+                        fptr->frag_off = htons(offset);
+                        if (skb->next != NULL)
+                                fptr->frag_off |= htons(IP6_MF);
+                        offset += (ntohs(ipv6h->payload_len) -
+                                   sizeof(struct frag_hdr));
+                }
+        }
+
+out:
+        return segs;
+}
+
+static struct sk_buff **ipv6_gro_receive(struct sk_buff **head,
+                                         struct sk_buff *skb)
+{
+        const struct net_offload *ops;
+        struct sk_buff **pp = NULL;
+        struct sk_buff *p;
+        struct ipv6hdr *iph;
+        unsigned int nlen;
+        unsigned int hlen;
+        unsigned int off;
+        int flush = 1;
+        int proto;
+        __wsum csum;
+
+        off = skb_gro_offset(skb);
+        hlen = off + sizeof(*iph);
+        iph = skb_gro_header_fast(skb, off);
+        if (skb_gro_header_hard(skb, hlen)) {
+                iph = skb_gro_header_slow(skb, hlen, off);
+                if (unlikely(!iph))
+                        goto out;
+        }
+
+        skb_gro_pull(skb, sizeof(*iph));
+        skb_set_transport_header(skb, skb_gro_offset(skb));
+
+        flush += ntohs(iph->payload_len) != skb_gro_len(skb);
+
+        rcu_read_lock();
+        proto = iph->nexthdr;
+        ops = rcu_dereference(inet6_offloads[proto]);
+        if (!ops || !ops->gro_receive) {
+                __pskb_pull(skb, skb_gro_offset(skb));
+                proto = ipv6_gso_pull_exthdrs(skb, proto);
+                skb_gro_pull(skb, -skb_transport_offset(skb));
+                skb_reset_transport_header(skb);
+                __skb_push(skb, skb_gro_offset(skb));
+
+                ops = rcu_dereference(inet6_offloads[proto]);
+                if (!ops || !ops->gro_receive)
+                        goto out_unlock;
+
+                iph = ipv6_hdr(skb);
+        }
+
+        NAPI_GRO_CB(skb)->proto = proto;
+
+        flush--;
+        nlen = skb_network_header_len(skb);
+
+        for (p = *head; p; p = p->next) {
+                const struct ipv6hdr *iph2;
+                __be32 first_word; /* <Version:4><Traffic_Class:8><Flow_Label:20> */
+
+                if (!NAPI_GRO_CB(p)->same_flow)
+                        continue;
+
+                iph2 = ipv6_hdr(p);
+                first_word = *(__be32 *)iph ^ *(__be32 *)iph2 ;
+
+                /* All fields must match except length and Traffic Class. */
+                if (nlen != skb_network_header_len(p) ||
+                    (first_word & htonl(0xF00FFFFF)) ||
+                    memcmp(&iph->nexthdr, &iph2->nexthdr,
+                           nlen - offsetof(struct ipv6hdr, nexthdr))) {
+                        NAPI_GRO_CB(p)->same_flow = 0;
+                        continue;
+                }
+                /* flush if Traffic Class fields are different */
+                NAPI_GRO_CB(p)->flush |= !!(first_word & htonl(0x0FF00000));
+                NAPI_GRO_CB(p)->flush |= flush;
+        }
+
+        NAPI_GRO_CB(skb)->flush |= flush;
+
+        csum = skb->csum;
+        skb_postpull_rcsum(skb, iph, skb_network_header_len(skb));
+
+        pp = ops->gro_receive(head, skb);
+
+        skb->csum = csum;
+
+out_unlock:
+        rcu_read_unlock();
+
+out:
+        NAPI_GRO_CB(skb)->flush |= flush;
+
+        return pp;
+}
+
+static int ipv6_gro_complete(struct sk_buff *skb)
+{
+        const struct net_offload *ops;
+        struct ipv6hdr *iph = ipv6_hdr(skb);
+        int err = -ENOSYS;
+
+        iph->payload_len = htons(skb->len - skb_network_offset(skb) -
+                                 sizeof(*iph));
+
+        rcu_read_lock();
+        ops = rcu_dereference(inet6_offloads[NAPI_GRO_CB(skb)->proto]);
+        if (WARN_ON(!ops || !ops->gro_complete))
+                goto out_unlock;
+
+        err = ops->gro_complete(skb);
+
+out_unlock:
+        rcu_read_unlock();
+
+        return err;
+}
+
+static struct packet_offload ipv6_packet_offload __read_mostly = {
+        .type = cpu_to_be16(ETH_P_IPV6),
+        .gso_send_check = ipv6_gso_send_check,
+        .gso_segment = ipv6_gso_segment,
+        .gro_receive = ipv6_gro_receive,
+        .gro_complete = ipv6_gro_complete,
+};
+
+void __init ipv6_offload_init(void)
+{
+        dev_add_offload(&ipv6_packet_offload);
+}
+
+void ipv6_offload_cleanup(void)
+{
+        dev_remove_offload(&ipv6_packet_offload);
+}